NEW YORK (Reuters) - A New York jury on Wednesday convicted a man of a rape committed 32 years ago based on DNA evidence hidden away in a case file and later linked to at least 11 other sexual assaults.

Clarence Williams, 58, escaped conviction at a 1974 trial because the victim, Kathleen Ham, never saw his face and said she could not identify him. Now he faces up to 50 years in prison for rape and robbery.

"Thirty years ago I thought I would never put myself through this again. But I felt I had a duty to right the wrong," Ham, 58, told a news conference regarding her decision to testify again.

"I am still in a little bit of shock. I was beaten up for two days on the stand years ago (by an aggressive defense lawyer). The DNA did not fade away. DNA does not lie," said Ham, who wanted her name made public because she is not ashamed.

Defense lawyer Michael Rubin tried to undermine the credibility of the New York City medical examiners conducting the DNA tests. He told the jury, "You cannot really rely on the laboratory used to conduct the DNA tests."

But the verdict was reached in less than two hours and after one unanimous vote, one juror said.

"A victim never forgets the crime," District Attorney Robert Morgenthau said. "A defendant should never be permitted to think he's home free just because of the passage of time."

Williams, who had several aliases, was convicted of raping another woman in 1974. But that was overturned because parts of his statement to police were mistakenly admitted into evidence.

With both rape cases pending retrial, Williams left New York and went undetected until last year, when he tried to buy a shotgun in Georgia and underwent a background check.

That alerted New York authorities, who had him extradited. A review of the case file produced the underpants Ham wore after the rape, allowing investigators to retrieve a DNA sample from a semen stain.

The DNA sample matched those from nine unsolved sexual assaults in Maryland and two in New Jersey, and Maryland authorities believe it could be tied to 21 attacks attributed to the "Silver Spring Rapist," prosecutors say.